Kingdom Monera & Microscopes Flashcards
First virus discovered
Tobacco mosaic virus: discovered by wendell Stanley
Characteristics that make a virus non-living
Outside a living call appear to be lifeless chemical and carry out no functions on their own
Can only reproduce inside a living cell (obligate intercellular parasite)
Occupies position between living and non-living
Viral structure
20nm-40nm
Do not contain: nucleus, inner membrane, or membrane bound organelles
Consist of: inner nucleic acid cord, outer protein coat called capsid (makes up 95% of virus and gives shape), often have lipid membrane called envelope
know how to draw
Virus shapes
- Helix
- Polyhedral
- Envelope
- Polyhedral head w/ cylindrical tail
Viral specificity
Describes how many kinds of organisms the virus is able to infect (host range)
Viruses identify host by fitting proteins on capsid with specific receptors on outside of host cell surface
Bacteriophage
Type of virus that infects bacteria cells
Ex: T4 bacteriophage
Lytic cycle
- Attachment and entrance: virus recognizes host, whole virus/nucleic acid enters
- Synthesis of protein and nucleic acid: virus takes over mechanism of replication
- Assembly: virus proteins and nucleic acids are assembled into particles
- Release: fully formed viruses burst cell and are released
- takes around 25-45 minutes
Lysogenic cycle
- Starts same as lytic cycle
- DNA becomes integrated into host cells DNA (now called prophage/provirus)
- DNA is replicated along with host cell
- Change in environment (temp, nutrients, damage…) causes cell to enter lytic cycle.
remains undetected
Non specific lines of defense
- skin
- mucous membranes
- oil and sweat glands
- gastric juice
Specific lines of defense
Immune response: antibodies are produced and bind to virus
Cells can then engulf and destroy
How viruses cause disease
How they are hard to treat
Attack cells, destroying them and thereby causing symptoms of the disease
They are active while safely inside our body and cannot be treated with antibodies, some become latent, they attack immune system, and mutate quickly
Vaccines
Are weakened or similar forms of the virus. These are injected into the person and their immune system easily fights off virus (produced antibodies)
Memory cell now recognizes virus and will fight it off before sickness is caused
Endemic
With us all the time (cold virus)
Epidemic
When a disease starts to spread rapidly
Pandemic
When a disease spreads throughout the world (small pox)
Retroviruses
Replicate nucleic acid in reverse of standard: use RNA to make DNA
Uses reverse transcriptase
- have envelope
Viroids
Tiny particles of pure RNA: causes disease in plants. There is no cure.
Prions
Are particles of proteins that cause some disease in animals: mutated gene
Prokaryotes
- do not have a nucleus
- do not have membrane bound organelles
- do have ribosomes (they differ)
- almost all smaller than smallest eukaryote
- most are single celled
- draw prokaryote*
Pili
Aid in:
- docking or sticking to surface
- exchange of DNA
Archaebacteria
- Live in extreme environments
- most species are harmless, some beneficial
- chemically distinct (cell walls, membranes, and ribosomal RNA)
- divided into 4 groups: methanogens, thermoacidophyles, chemosynthesizers, and extreme halophiles
Methanogens
- produce methane
- live in oxygen free environment
Found in: swamps, marshes, mammals - used to treat sewage and purify waste water
Thermoacidophyles
- live in extremely hot (6-250 degrees Celsius) and acidic water